The present invention relates to a woven security label, and particularly to a woven security label that reversibly emits a straight color line when radiated with specific UV light. In the woven label, a warp or weft yarn consisting of one or more pieces of detectable filament is interwoven with ordinary warp and weft threads of synthetic fiber.
As quality or design for articles clothing become more diversified, it is harder for consumers to select and purchase desired articles. It becomes clear that famous trademarks and popular character brands goods are preferred for purchase and requested by a consumer, so the value of the famous trademarks or popular character brands has risen more and more. With rising value, the number of dealers who use and infringe famous trademarks and popular character brands on counterfeit goods is on the increase. Thus, manufacturers or distributors must attach security label to their marketing articles such as goods or packages in order to prove their authenticity.
In a conventional security device such as woven label, it is well known to interweave photochromic yarn into the label, as described in European Patent No. 328320. The photochromic yarn is substantially colorless when irradiated with visible light and reversibly converts to a colored state when irradiated with UV light. The photochromic yarn consists of fiber containing one or more photochromic compounds or mixture thereof. Two classes of suitable photochromic compounds are spiro-pyrans and spiro-oxazines. It is not possible to make them easily in large quantities, so it is very expensive to use them. Furthermore, there is the additional problem of indistinct color-change with UV light.
It has also been suggested weaving threads using inorganic fluorescent substances into security label with letters, symbols or pattern, in Japanese Patent Open Publication No. 6-306727. In this publication, however, it is not evident to describe a method for making the threads and using the inorganic fluorescent substance at all.